Our research focuses on the development and use of animal model systems to study the regulation of gastrointestinal functions. Of particular concern are the regulation of intestinal absorption and metabolism of nutrients, and the alteration of these normally occurring events in response to oral exposure to biologically active environmental toxins. Currently, our investigations involve the systematic examination of the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin) on normal lipid assimilation. The mechanism of the physiologic changes is monitored with a combination of in vitro and in vivo techniques. In particular, our studies include examination of 1) serum lipid, lipoprotein and triglyceride hydrolase, 2) relationship between food deprivation and hyperlipidemia, 3) mortality after chemically induced changes in serum and/or liver lipids, 4) binding and internalization of serum lipoproteins by liver, and 5) epithelial cell membrane proteins and glycoproteins.